/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */
package com.feilong.lib.org.apache.http.impl.auth;

import com.feilong.lib.org.apache.http.Header;
import com.feilong.lib.org.apache.http.HttpRequest;
import com.feilong.lib.org.apache.http.auth.AUTH;
import com.feilong.lib.org.apache.http.auth.AuthenticationException;
import com.feilong.lib.org.apache.http.auth.Credentials;
import com.feilong.lib.org.apache.http.auth.InvalidCredentialsException;
import com.feilong.lib.org.apache.http.auth.MalformedChallengeException;
import com.feilong.lib.org.apache.http.auth.NTCredentials;
import com.feilong.lib.org.apache.http.message.BufferedHeader;
import com.feilong.lib.org.apache.http.util.Args;
import com.feilong.lib.org.apache.http.util.CharArrayBuffer;

/**
 * NTLM is a proprietary authentication scheme developed by Microsoft
 * and optimized for Windows platforms.
 *
 * @since 4.0
 */
public class NTLMScheme extends AuthSchemeBase{

    enum State{
        UNINITIATED, CHALLENGE_RECEIVED, MSG_TYPE1_GENERATED, MSG_TYPE2_RECEVIED, MSG_TYPE3_GENERATED, FAILED,
    }

    private final NTLMEngine engine;

    private State            state;

    private String           challenge;

    public NTLMScheme(final NTLMEngine engine){
        super();
        Args.notNull(engine, "NTLM engine");
        this.engine = engine;
        this.state = State.UNINITIATED;
        this.challenge = null;
    }

    /**
     * @since 4.3
     */
    public NTLMScheme(){
        this(new NTLMEngineImpl());
    }

    @Override
    public String getSchemeName(){
        return "ntlm";
    }

    @Override
    public String getParameter(final String name){
        // String parameters not supported
        return null;
    }

    @Override
    public String getRealm(){
        // NTLM does not support the concept of an authentication realm
        return null;
    }

    @Override
    public boolean isConnectionBased(){
        return true;
    }

    @Override
    protected void parseChallenge(final CharArrayBuffer buffer,final int beginIndex,final int endIndex) throws MalformedChallengeException{
        this.challenge = buffer.substringTrimmed(beginIndex, endIndex);
        if (this.challenge.isEmpty()){
            if (this.state == State.UNINITIATED){
                this.state = State.CHALLENGE_RECEIVED;
            }else{
                this.state = State.FAILED;
            }
        }else{
            if (this.state.compareTo(State.MSG_TYPE1_GENERATED) < 0){
                this.state = State.FAILED;
                throw new MalformedChallengeException("Out of sequence NTLM response message");
            }else if (this.state == State.MSG_TYPE1_GENERATED){
                this.state = State.MSG_TYPE2_RECEVIED;
            }
        }
    }

    @Override
    public Header authenticate(final Credentials credentials,final HttpRequest request) throws AuthenticationException{
        NTCredentials ntcredentials = null;
        try{
            ntcredentials = (NTCredentials) credentials;
        }catch (final ClassCastException e){
            throw new InvalidCredentialsException(
                            "Credentials cannot be used for NTLM authentication: " + credentials.getClass().getName());
        }
        String response = null;
        if (this.state == State.FAILED){
            throw new AuthenticationException("NTLM authentication failed");
        }else if (this.state == State.CHALLENGE_RECEIVED){
            response = this.engine.generateType1Msg(ntcredentials.getDomain(), ntcredentials.getWorkstation());
            this.state = State.MSG_TYPE1_GENERATED;
        }else if (this.state == State.MSG_TYPE2_RECEVIED){
            response = this.engine.generateType3Msg(
                            ntcredentials.getUserName(),
                            ntcredentials.getPassword(),
                            ntcredentials.getDomain(),
                            ntcredentials.getWorkstation(),
                            this.challenge);
            this.state = State.MSG_TYPE3_GENERATED;
        }else{
            throw new AuthenticationException("Unexpected state: " + this.state);
        }
        final CharArrayBuffer buffer = new CharArrayBuffer(32);
        if (isProxy()){
            buffer.append(AUTH.PROXY_AUTH_RESP);
        }else{
            buffer.append(AUTH.WWW_AUTH_RESP);
        }
        buffer.append(": NTLM ");
        buffer.append(response);
        return new BufferedHeader(buffer);
    }

    @Override
    public boolean isComplete(){
        return this.state == State.MSG_TYPE3_GENERATED || this.state == State.FAILED;
    }

}
